July 2003
Predetermined winners and losers in the Ice Age extinction game The Quaternary ice ages caused severe decimation of the European tree flora. Of the diverse pre-Ice Age tree flora only a minority of the genera are still widespread in Europe. Most of the remainder have been lost altogether from the European flora and now only occurs in Asia and/or North America, although some persist as relicts in southern Europe. In the July issue of Ecology Letters, Svenning provides evidence that the Ice Age fate of European cool-temperate tree genera was predetermined by evolutionarily conservative limits to their climatic tolerances.As estimated from their modern distribution outside Europe, still widespread genera are more cold tolerant than extinct and relictual genera, while relictual genera are more drought tolerant than extinct genera. An important lesson from these findings is to expect only limited evolutionary adaptability of tree genera in the face of future climatic changes. | |